Chapter 3: Active Children and Adolescents

Regular physical activity in children and adolescents promotes health
and fitness. Compared to those who are inactive, physically active youth have
higher levels of cardiorespiratory fitness and stronger muscles. They also
typically have lower body fatness. Their bones are stronger, and they may have
reduced symptoms of anxiety and depression.

Youth who are regularly active also have a better chance of a healthy
adulthood. Children and adolescents don't usually develop chronic
diseases, such as heart disease, hypertension, type 2 diabetes, or
osteoporosis. However, risk factors for these diseases can begin to develop
early in life. Regular physical activity makes it less likely that these risk
factors will develop and more likely that children will remain healthy as
adults.

Youth can achieve substantial health benefits by doing moderate- and
vigorous-intensity physical activity for periods of time that add up to 60
minutes (1 hour) or more each day. This activity should include aerobic
activity as well as age-appropriate muscle- and bone–strengthening
activities. Although current science is not complete, it appears that, as with
adults, the total amount of physical activity is more important for achieving
health benefits than is any one component (frequency, intensity, or duration)
or specific mix of activities (aerobic, muscle-strengthening, bone
strengthening). Even so, bone-strengthening activities remain especially
important for children and young adolescents because the greatest gains in bone
mass occur during the years just before and during puberty. In addition, the
majority of peak bone mass is obtained by the end of adolescence.

This chapter provides physical activity guidance for children and
adolescents aged 6 to 17, and focuses on physical activity beyond baseline
activity.

Parents and other adults who work with or care for youth should be
familiar with the Guidelines in this chapter. These adults should be aware
that, as children become adolescents, they typically reduce their physical
activity. Adults play an important role in providing age-appropriate
opportunities for physical activity. In doing so, they help lay an important
foundation for life-long, health-promoting physical activity. Adults need to
encourage active play in children and encourage sustained and structured
activity as children grow older.

Key Guidelines for Children and Adolescents

Children and adolescents should do 60 minutes (1 hour) or more of
physical activity daily.

Aerobic: Most of the 60 or more minutes a day
should be either moderate- or vigorous-intensity aerobic physical activity, and
should include vigorous-intensity physical activity at least 3 days a week.

Muscle-strengthening: As part of their 60 or
more minutes of daily physical activity, children and adolescents should
include muscle-strengthening physical activity on at least 3 days of the week.

Bone-strengthening: As part of their 60 or
more minutes of daily physical activity, children and adolescents should
include bone-strengthening physical activity on at least 3 days of the week.

It is important to encourage young people to participate in
physical activities that are appropriate for their age, that are enjoyable, and
that offer variety.

Explaining the Guidelines

Types of Activity

The Guidelines for children and adolescents focus on three types of
activity: aerobic, muscle-strengthening, and bone-strengthening. Each type has
important health benefits.

Aerobic activities are those in which young people
rhythmically move their large muscles. Running, hopping, skipping, jumping
rope, swimming, dancing, and bicycling are all examples of aerobic activities.
Aerobic activities increase cardiorespiratory fitness. Children often do
activities in short bursts, which may not technically be aerobic activities.
However, this document will also use the term aerobic to refer to these brief
activities.

Muscle-strengthening activities make muscles do more
work than usual during activities of daily life. This is called
"overload," and it strengthens the muscles. Muscle-strengthening
activities can be unstructured and part of play, such as playing on playground
equipment, climbing trees, and playing tug-of-war. Or these activities can be
structured, such as lifting weights or working with resistance bands.

Bone-strengthening activities produce a force on
the bones that promotes bone growth and strength. This force is commonly
produced by impact with the ground. Running, jumping rope, basketball, tennis,
and hopscotch are all examples of bone strengthening activities. As these
examples illustrate, bone-strengthening activities can also be aerobic and
muscle-strengthening.

How Age Influences Physical Activity in Children and Adolescents

Children and adolescents should meet the Guidelines by doing activity
that is appropriate for their age. Their natural patterns of movement differ
from those of adults. For example, children are naturally active in an
intermittent way, particularly when they do unstructured active play. During
recess and in their free play and games, children use basic aerobic and
bone-strengthening activities, such as running, hopping, skipping, and jumping,
to develop movement patterns and skills. They alternate brief periods of
moderate- and vigorous-intensity physical activity with brief periods of rest.
Any episode of moderate- or vigorous–intensity physical activity, however
brief, counts toward the Guidelines.

Children also commonly increase muscle strength through unstructured
activities that involve lifting or moving their body weight or working against
resistance. Children don't usually do or need formal muscle-strengthening
programs, such as lifting weights.

Regular physical activity in children and adolescents promotes a
healthy body weight and body composition.

As children grow into adolescents, their patterns of physical activity
change. They are able to play organized games and sports and are able to
sustain longer periods of activity. But they still commonly do intermittent
activity, and no period of moderate- or vigorous-intensity activity is too
short to count toward the Guidelines.

Adolescents may meet the Guidelines by doing free play, structured
programs, or both. Structured exercise programs can include aerobic activities,
such as playing a sport, and muscle-strengthening activities, such as lifting
weights, working with resistance bands, or using body weight for resistance
(such as push-ups, pull-ups, and sit-ups). Muscle-strengthening activities
count if they involve a moderate to high level of effort and work the major
muscle groups of the body: legs, hips, back, abdomen, chest, shoulders, and
arms.

Levels of Intensity for Aerobic Activity

Children and adolescents can meet the Guidelines by doing a combination
of moderate- and vigorous intensity aerobic physical activities or by doing
only vigorous-intensity aerobic physical activities.

Youth should not do only moderate-intensity activity. It's
important to include vigorous-intensity activities because they cause more
improvement in cardiorespiratory fitness.

The intensity of aerobic physical activity can be defined on either an
absolute or a relative scale. Either scale can be used to monitor the intensity
of aerobic physical activity:

For More Information

See Appendix 1 for more information on using absolute or relative
intensity.

Absolute intensity is based on the rate of energy
expenditure during the activity, without taking into account a person's
cardiorespiratory fitness.

Relative intensity describes a person's level of effort relative
to his or her fitness. As a rule of thumb, on a scale of 0 to 10, where sitting
is 0 and the highest level of effort possible is 10, moderate-intensity
activity is a 5 or 6. Young people doing moderate-intensity activity will
notice that their hearts are beating faster than normal and they are breathing
harder than normal. Vigorous-intensity activity is at a level of 7 or 8. Youth
doing vigorous-intensity activity will feel their heart beating much faster
than normal and they will breathe much harder than normal.

When adults supervise children, they generally can't ascertain a
child's heart or breathing rate. But they can observe whether a child is
doing an activity which, based on absolute energy expenditure, is considered to
be either moderate or vigorous. For example, a child walking briskly to school
is doing moderate-intensity activity. A child running on the playground is
doing vigorous-intensity activity. The table on page 18 includes examples of
activities classified by absolute intensity. It shows that the same activity
can be moderate or vigorous intensity, depending on factors such as speed (for
example bicycling slowly or fast).

Examples of Moderate- and Vigorous-Intensity Aerobic Physical
Activities and Muscle- and Bone-Strengthening Activities for Children and
Adolescents

Note: Some activities, such as bicycling, can be
moderate or vigorous intensity, depending upon level of effort

Physical Activity and Healthy Weight

Regular physical activity in children and adolescents promotes a
healthy body weight and body composition.

Exercise training in overweight or obese youth can improve body
composition by reducing overall levels of fatness as well as abdominal fatness.
Research studies report that fatness can be reduced by regular physical
activity of moderate to vigorous intensity 3 to 5 times a week, for 30 to 60
minutes.

Meeting the Guidelines

American youth vary in their physical activity participation. Some
don't participate at all, others participate in enough activity to meet
the Guidelines, and some exceed the Guidelines.

Children and adolescents can meet the Physical Activity Guidelines and
become regularly physically active in many ways.

One practical strategy to promote activity in youth is to replace
inactivity with activity whenever possible. For example, where appropriate and
safe, young people should walk or bicycle to school instead of riding in a car.
Rather than just watching sporting events on television, young people should
participate in age-appropriate sports or games.

Children and adolescents who do not meet the
Guidelines should slowly increase their activity in small steps and in
ways that they enjoy. A gradual increase in the number of days and the time
spent being active will help reduce the risk of injury.

Children and adolescents who meet the Guidelines
should continue being active on a daily basis and, if appropriate, become even
more active. Evidence suggests that even more than 60 minutes of activity every
day may provide additional health benefits.

Children and adolescents who exceed the Guidelines
should maintain their activity level and vary the kinds of activities they do
to reduce the risk of overtraining or injury.

Children and adolescents with disabilities are more likely to be
inactive than those without disabilities. Youth with disabilities should work
with their health-care provider to understand the types and amounts of physical
activity appropriate for them. When possible, children and adolescents with
disabilities should meet the Guidelines. When young people are not able to
participate in appropriate physical activities to meet the Guidelines, they
should be as active as possible and avoid being inactive.

Getting and Staying Active: Real-Life Examples

Children and adolescents can meet the Physical Activity Guidelines and
become regularly physically active in many ways. Here are just two examples
showing how a child and an adolescent can be physically active for at least 60
minutes each day over the course of a week.

These examples illustrate that even though the activity patterns are
different, each young person is meeting the Guidelines by getting the
equivalent of at least 60 minutes or more of aerobic activity each day that is
at least moderate intensity. Both are also doing vigorous-intensity,
muscle-strengthening, and bone strengthening activities on at least 3 days a
week.

Harold: A 7-Year-Old Child

Harold participates in many types of physical activities in many
places. For example, during physical education class, he jumps rope and does
gymnastics and sit-ups. During recess, he plays on the playground—often by
doing activities that require running and climbing. He also likes to play
soccer with his friends and family. When Harold gets home from school, he likes
to engage in active play (playing tag) and ride his bicycle with his friends
and family.

Harold gets 60 minutes of physical activity each day that is at least
moderate intensity. He participates in the following activities each day:

Monday: Walks to and from school (20 minutes), plays actively with
family (20 minutes), jumps rope (10 minutes), does gymnastics (10 minutes).

Tuesday: Walks to and from school (20 minutes), plays on playground (25
minutes), climbs on playground equipment (15 minutes).

Maria: A 16-Year-Old Adolescent

Maria participates in many types of physical activities in many places.
For example, during physical education class, she plays tennis and does sit-ups
and push-ups. She also likes to play basketball at the YMCA, do yoga, and go
dancing with friends. Maria likes to take her dog on walks and hikes.

Maria gets 60 or more minutes of daily physical activity that is at
least moderate intensity. She participates in the following activities each
day: